The present invention relates to an image reading apparatus comprising an image reading means which reads an image in a reading area including an original document area to obtain image data, and a memory means which stores the image data obtained by the aforesaid image reading means, and specifically to an image reading apparatus which may correct inclination of the original document, if any.
The image reading apparatus which reads the image in the reading area including an original document area and comprises an image reading means which obtains image data and a memory means which stores the image data obtained by the aforesaid image reading means is employed in scanners, facsimile machines, digital copiers, and the like. Generally speaking, such an image reading apparatus is constituted in such a manner that an original document is placed on the document platen and the image information of the original document on the document platen is read. At the time, the image reading apparatus reads image data in the larger area (hereinafter referred to as reading area) than the placed original document area (hereinafter referred to as original document area).
In such an image reading apparatus, when an original document is placed with inclination, of read image data, the image data in the original document area includes inclination data. When an image or the like is formed employing the resulting image data, the formed image may be discontinuous, and no exact image formation may be carried out. On account of this, heretofore, an image reading apparatus has been proposed, in which for image data of inclined original document area, inclination correction (correcting inclination) is carried out. In the case of correcting the inclination, it is required to detect the inclination of the original document. Regarding the detection of the inclination of the original document, there have been various types of proposals.
For example, Japanese Patent Publication Open to Public Inspection No. 2-25863 proposes an image reading apparatus in which prior to reading image data, inclination of the original document is detected by pre-scanning, employing a sensor which detects any inclination of the original document. Further, Japanese Patent Publication Open to Public Inspection No. 7-262312 proposes an image reading apparatus in which any inclination of the original document is detected on the basis of the arrangement of text characters obtained from the read image data.
In the image reading apparatus proposed by the aforesaid Japanese Patent Publication Open to Public Inspection No. 2-25863, an exclusive sensor to detect the inclination is required, at an increase of cost. Furthermore, pre-scanning, as an additional mechanical motion, is carried at an increase of time. Furthermore, in the image reading apparatus proposed in Japanese Patent Publication Open to Public Inspection No. 7-262312, problems are caused in which in order to check the arrangement of characters, complicated image processing and image recognition techniques are required, and due to this, excessive processing time is required, and when characters on an original document are intentionally declined, defective operation is caused.
Accordingly, an object of the present invention is to provide an image reading apparatus which readily detects any inclination without the installment of an exclusive sensor, additional mechanical motion and complicated image recognition processing.
The aforesaid object can be accomplished by the structure below.
In an image reading apparatus comprising an image reading means which reads an image in a reading area including an original document area, to obtain image data and a memory means which stores the image data obtained by the aforesaid image reading means, an image reading apparatus characterized in comprising an edge detecting means which detects a plurality of edges in the aforesaid original document area, on the basis of the image data obtained by the aforesaid image reading means, a calculation means which calculates the degree of inclination of an original document on the basis of a plurality of edges detected by the aforesaid edge detecting means, and an inclination correcting means which corrects for the inclination based on the inclination of the original document calculated by the aforesaid calculation means, for at least the image data in the aforesaid original document area among the image data stored by the aforesaid memory means.